TouchDAW offers two layers of functionality: DAW control plus some general purpose MIDI tools. These two parts of the app are independent from each other and can be used completely separate: Each part may connect to separate target applications, eventually even running on separate computers. Most likely though, you will use them in parallel, talking to the same program: To record MIDI in the controlled DAW, to interact with one of its synthesizers using MIDI generated by the phone's accelerometer, to do some live remixing or whatever else may come to mind.

DAW control:

The first functional layer is the DAW controller. This puts much of the functionality of a 5 - 1500 Euro piece of mono-functional hardware onto your phone or tablet. The DAW controller is also the screen that the app will start up with. It emulates a standard hardware control surface for common digital audio workstations and gives you control over a large set of parameters in the controlled software. In particular you get full control over the DAW's mixer (track volume, panorama, automation, solo and mute settings), transport, effects, equalizers, virtual instruments and bus assignments. Additionally you will be able to save projects, perform undo's and redo's etc.

What exactly is accessible depends on the controlled DAW to some degree although basic functionality should work across products. TouchDAW has dedicated support for 16 of the most popular DAW programs. That is: it knows how these products combine controls to achieve certain things, how they name their functions, use the displays etc. This is of particular importance on the phone interface given TouchDAW can only show one channel at a time and has very little screen space available for monitoring what's going on inside the DAW.

MIDI utilities:

The second part of the app is made up of some general purpose MIDI controllers. TouchDAW includes a multitouch keyboard with pitch and controller support, a MIDI mixer, multitouch launchpads and xy controller pads that can also map a phone's sensors to MIDI controllers.

Two MIDI connections:

Both parts of the app are independent from each other and use separate MIDI connections. What is particularlly important to understand is that DAW control essentially requires a "closed circuit", bidirectional MIDI link between the app and the DAW. No other MIDI source should interfere with the communication between the two and you will want to keep control data away from your "musical" data flow alike.

Performance, battery use etc.:

TouchDAW can potentially generate a lot of traffic over WIFI and as it is dealing with music you will want it to be fast and responsive. Keep in mind that on smartphones there are a lot of other things happening next to the app currently running in front. For best performance you should consider turning off things that are not currently needed. Don't let the phone download email or check your friends' facebook status when you are performing on stage or recording.
MIDI communication over RTP requires a constant uninterrupted WIFI connection. A lot of phones shut down WIFI when going into energy saving mode and thus will break the connection. You may need to let TouchDAW disable sleep mode and have your charger at hand when using the app for longer periods.